The invention relates to product manufacturing, and more particularly to systems and methods for manufacturing control using radio frequency identification.
In a conventional semiconductor manufacturing environment, a wafer lot is assigned a lot identification number (lot ID), and processing tools execute processes accordingly. In open cassette environment without SMIF (Standard Mechanical InterFace) mechanisms, the lot ID is typically identified visually and input manually by an operator. When an erroneous lot ID is input, the wafer lot may be processed improperly, requiring reprocessing or scrapping.
Currently barcodes are used for identifying lot IDs of wafer lots in such environment for cost issue. In this case, an operator uses a hand-held scanner to read the barcodes. Although this method is an improvement over purely manual processes, it can be difficult for complete implementation, partly due to the need for close proximity and proper alignment between the scanner and barcodes. It also requires an operator to participate in the load-identification process. The operator may need to exit the transport vehicle to scan the barcodes manually, slowing down process operations. Certain locations, such as high loading docks, are particularly problematic for implementing barcodes due to the need for close proximity between the barcode tags and the reader. As a result, loads in those areas are often visually identified instead. After the barcode tag is scanned manually, the corresponding wafer carrier is put into a loading port of a processing tool by the operator. Because the barcode scanning and lot loading is executed separately by the operator, it is possible for the operator to scan barcode of one carrier and load another. In this case, the loaded wafer lot is processed according to a recipe corresponding to the scanned barcode.
Radio-frequency identification (“RFID”) tag systems have been used in inventory tracking, wherein RFID tags are attached to an object or location. A RFID tag comprises a non-volatile memory storing information identifying the object or location and electronic circuitry interacting with a RFID interrogator, detecting the presence of a RFID tag and reading the identification information therefrom. A RFID interrogator typically comprises an RF transceiver transmitting interrogation signals to RFID tags and receiving response signals therefrom, one or more antennae connected to the transceiver, and associated decoders and encoders reading and writing encoded information in the received and transmitted RF signals, respectively.
In a semiconductor manufacturing environment with SMIF mechanisms, the RFID interrogator is typically equipped with optical sensor, and activated when the optical sensor detects an item. The RFID technique has drawbacks when applied in the environment without SMIF mechanisms. The RFID interrogator retrieves information stored in a RFID tag when the tag is in proximity. When the information, such as lot ID, is retrieved by a RFID interrogator associated with a processing tool, an automatic transport device may be activated to load a corresponding wafer lot onto the processing tool. The RFID interrogator is activated when a wafer carrier passes by, and a transport device activated thereby may be hazardous to an operator.